Since the discovery of penicillin, pharmaceutical companies have produced more than one hundred antibacterial agents to combat a wide variety of bacterial infections. In the past several years, there has been rapid emergence of bacterial resistance to several of these antibiotics. The multi-drug resistance among these bacterial pathogens may also be due to mutation leading to more virulent clinical isolations. The most disturbing milestone has been the acquisition of resistance to vancomycin, an antibiotic generally regarded as the agent of last resort for serious Gram-positive infections. It is believed that the proliferation of multidrug resistant bacteria is brought on by a wide spread use, or rather misuse, of existing antibacterials, further exacerbated by the use of antibacterials as feed supplements in farm animals and poultry.
Bacterial infection is a long-term problem that requires innovative new therapeutics. Moreover, in view of the increasing reports of vancomycin-resistant bacterial isolates and growing problem of bacterial resistance, there is an urgent need for new molecular entities effective against the emerging bacterial organisms. The growing problem of multidrug resistance has intensified the search for new antibiotics. Yet new drugs are difficult to develop and bacterial strains resistant to new drugs may quickly emerge. For example, soon after introduction of Linezolid (Zyovx™, Pharmacia Upjohn), a representative of a first entirely new class of antibacterials released into the market over the past 30 years, clinics reported cases of resistance (Lancet 2001, 358(9277): 207–8). Resistant strains have been selected in the lab where a target site alteration was found to reduce drug binding (Antimicrob. Agents Chemother. 2001, 3(3): 288–294).
Oxazolidinones, a class of compounds that includes Linezolid, contain an oxazolidinone moiety

For example, compounds of the generalized structure
are known in the prior art. In these compounds, a heterocyclic moiety (Het) is connected to the oxazolidinone moiety through an aromatic nucleus (Ar). Specific examples of oxazolidinone compounds are disclosed in International publication nos. WO 01/09107, WO 97/27188, WO 96/13502 and WO 96/13502. Certain oxazolidinones are believed to be useful as antibacterials (J. Med. Chem., 1996, 39, 673), antihistamines and anti allergic agents (EP 291,244), anticonvulsants (DE 3,915,184), as well as for treating cognition disorders, anti psychotics, anti platelet aggregators, antidepressants, sedatives, hypnotics, and as monoamine oxidase inhibitors (WO 97/13768).